Revert "third_party/protobuf: Update to HEAD (83d681ee2c)"

third_party/protobuf/python/google/protobuf/pyext/message.cc

Index: third_party/protobuf/python/google/protobuf/pyext/message.cc
diff --git a/third_party/protobuf/python/google/protobuf/pyext/message.cc b/third_party/protobuf/python/google/protobuf/pyext/message.cc
index 4f3abc84bedce3584629ef4d98d52792e3dcbdaa..83c151ff626aabab287e8bfe39b4b8b80e99791f 100644
--- a/third_party/protobuf/python/google/protobuf/pyext/message.cc
+++ b/third_party/protobuf/python/google/protobuf/pyext/message.cc
@@ -63,12 +63,11 @@
 #include <google/protobuf/pyext/repeated_composite_container.h>
 #include <google/protobuf/pyext/repeated_scalar_container.h>
 #include <google/protobuf/pyext/map_container.h>
-#include <google/protobuf/pyext/message_factory.h>
-#include <google/protobuf/pyext/safe_numerics.h>
 #include <google/protobuf/pyext/scoped_pyobject_ptr.h>
 #include <google/protobuf/stubs/strutil.h>
 
 #if PY_MAJOR_VERSION >= 3
+  #define PyInt_Check PyLong_Check
   #define PyInt_AsLong PyLong_AsLong
   #define PyInt_FromLong PyLong_FromLong
   #define PyInt_FromSize_t PyLong_FromSize_t
@@ -92,6 +91,8 @@ namespace protobuf {
 namespace python {
 
 static PyObject* kDESCRIPTOR;
+static PyObject* k_extensions_by_name;
+static PyObject* k_extensions_by_number;
 PyObject* EnumTypeWrapper_class;
 static PyObject* PythonMessage_class;
 static PyObject* kEmptyWeakref;
@@ -126,6 +127,19 @@ static bool AddFieldNumberToClass(
 
 // Finalize the creation of the Message class.
 static int AddDescriptors(PyObject* cls, const Descriptor* descriptor) {
+  // If there are extension_ranges, the message is "extendable", and extension
+  // classes will register themselves in this class.
+  if (descriptor->extension_range_count() > 0) {
+    ScopedPyObjectPtr by_name(PyDict_New());
+    if (PyObject_SetAttr(cls, k_extensions_by_name, by_name.get()) < 0) {
+      return -1;
+    }
+    ScopedPyObjectPtr by_number(PyDict_New());
+    if (PyObject_SetAttr(cls, k_extensions_by_number, by_number.get()) < 0) {
+      return -1;
+    }
+  }
+
   // For each field set: cls.<field>_FIELD_NUMBER = <number>
   for (int i = 0; i < descriptor->field_count(); ++i) {
     if (!AddFieldNumberToClass(cls, descriptor->field(i))) {
@@ -230,12 +244,6 @@ static PyObject* New(PyTypeObject* type,
     return NULL;
   }
 
-  // Messages have no __dict__
-  ScopedPyObjectPtr slots(PyTuple_New(0));
-  if (PyDict_SetItemString(dict, "__slots__", slots.get()) < 0) {
-    return NULL;
-  }
-
   // Build the arguments to the base metaclass.
   // We change the __bases__ classes.
   ScopedPyObjectPtr new_args;
@@ -292,19 +300,16 @@ static PyObject* New(PyTypeObject* type,
   newtype->message_descriptor = descriptor;
   // TODO(amauryfa): Don't always use the canonical pool of the descriptor,
   // use the MessageFactory optionally passed in the class dict.
-  PyDescriptorPool* py_descriptor_pool =
-      GetDescriptorPool_FromPool(descriptor->file()->pool());
-  if (py_descriptor_pool == NULL) {
+  newtype->py_descriptor_pool = GetDescriptorPool_FromPool(
+      descriptor->file()->pool());
+  if (newtype->py_descriptor_pool == NULL) {
     return NULL;
   }
-  newtype->py_message_factory = py_descriptor_pool->py_message_factory;
-  Py_INCREF(newtype->py_message_factory);
+  Py_INCREF(newtype->py_descriptor_pool);
 
-  // Register the message in the MessageFactory.
-  // TODO(amauryfa): Move this call to MessageFactory.GetPrototype() when the
-  // MessageFactory is fully implemented in C++.
-  if (message_factory::RegisterMessageClass(newtype->py_message_factory,
-                                            descriptor, newtype) < 0) {
+  // Add the message to the DescriptorPool.
+  if (cdescriptor_pool::RegisterMessageClass(newtype->py_descriptor_pool,
+                                             descriptor, newtype) < 0) {
     return NULL;
   }
 
@@ -316,8 +321,8 @@ static PyObject* New(PyTypeObject* type,
 }
 
 static void Dealloc(CMessageClass *self) {
-  Py_XDECREF(self->py_message_descriptor);
-  Py_XDECREF(self->py_message_factory);
+  Py_DECREF(self->py_message_descriptor);
+  Py_DECREF(self->py_descriptor_pool);
   Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
 }
 
@@ -342,61 +347,6 @@ static int InsertEmptyWeakref(PyTypeObject *base_type) {
 #endif  // PY_MAJOR_VERSION >= 3
 }
 
-// The _extensions_by_name dictionary is built on every access.
-// TODO(amauryfa): Migrate all users to pool.FindAllExtensions()
-static PyObject* GetExtensionsByName(CMessageClass *self, void *closure) {
-  const PyDescriptorPool* pool = self->py_message_factory->pool;
-
-  std::vector<const FieldDescriptor*> extensions;
-  pool->pool->FindAllExtensions(self->message_descriptor, &extensions);
-
-  ScopedPyObjectPtr result(PyDict_New());
-  for (int i = 0; i < extensions.size(); i++) {
-    ScopedPyObjectPtr extension(
-        PyFieldDescriptor_FromDescriptor(extensions[i]));
-    if (extension == NULL) {
-      return NULL;
-    }
-    if (PyDict_SetItemString(result.get(), extensions[i]->full_name().c_str(),
-                             extension.get()) < 0) {
-      return NULL;
-    }
-  }
-  return result.release();
-}
-
-// The _extensions_by_number dictionary is built on every access.
-// TODO(amauryfa): Migrate all users to pool.FindExtensionByNumber()
-static PyObject* GetExtensionsByNumber(CMessageClass *self, void *closure) {
-  const PyDescriptorPool* pool = self->py_message_factory->pool;
-
-  std::vector<const FieldDescriptor*> extensions;
-  pool->pool->FindAllExtensions(self->message_descriptor, &extensions);
-
-  ScopedPyObjectPtr result(PyDict_New());
-  for (int i = 0; i < extensions.size(); i++) {
-    ScopedPyObjectPtr extension(
-        PyFieldDescriptor_FromDescriptor(extensions[i]));
-    if (extension == NULL) {
-      return NULL;
-    }
-    ScopedPyObjectPtr number(PyInt_FromLong(extensions[i]->number()));
-    if (number == NULL) {
-      return NULL;
-    }
-    if (PyDict_SetItem(result.get(), number.get(), extension.get()) < 0) {
-      return NULL;
-    }
-  }
-  return result.release();
-}
-
-static PyGetSetDef Getters[] = {
-  {"_extensions_by_name", (getter)GetExtensionsByName, NULL},
-  {"_extensions_by_number", (getter)GetExtensionsByNumber, NULL},
-  {NULL}
-};
-
 }  // namespace message_meta
 
 PyTypeObject CMessageClass_Type = {
@@ -429,7 +379,7 @@ PyTypeObject CMessageClass_Type = {
   0,                                   // tp_iternext
   0,                                   // tp_methods
   0,                                   // tp_members
-  message_meta::Getters,               // tp_getset
+  0,                                   // tp_getset
   0,                                   // tp_base
   0,                                   // tp_dict
   0,                                   // tp_descr_get
@@ -565,10 +515,23 @@ int ForEachCompositeField(CMessage* self, Visitor visitor) {
 
 // ---------------------------------------------------------------------
 
+// Constants used for integer type range checking.
+PyObject* kPythonZero;
+PyObject* kint32min_py;
+PyObject* kint32max_py;
+PyObject* kuint32max_py;
+PyObject* kint64min_py;
+PyObject* kint64max_py;
+PyObject* kuint64max_py;
+
 PyObject* EncodeError_class;
 PyObject* DecodeError_class;
 PyObject* PickleError_class;
 
+// Constant PyString values used for GetAttr/GetItem.
+static PyObject* k_cdescriptor;
+static PyObject* kfull_name;
+
 /* Is 64bit */
 void FormatTypeError(PyObject* arg, char* expected_types) {
   PyObject* repr = PyObject_Repr(arg);
@@ -582,126 +545,68 @@ void FormatTypeError(PyObject* arg, char* expected_types) {
   }
 }
 
-void OutOfRangeError(PyObject* arg) {
-  PyObject *s = PyObject_Str(arg);
-  if (s) {
-    PyErr_Format(PyExc_ValueError,
-                 "Value out of range: %s",
-                 PyString_AsString(s));
-    Py_DECREF(s);
-  }
-}
-
-template<class RangeType, class ValueType>
-bool VerifyIntegerCastAndRange(PyObject* arg, ValueType value) {
-  if GOOGLE_PREDICT_FALSE(value == -1 && PyErr_Occurred()) {
-    if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
-      // Replace it with the same ValueError as pure python protos instead of
-      // the default one.
-      PyErr_Clear();
-      OutOfRangeError(arg);
-    }  // Otherwise propagate existing error.
-    return false;
-  }
-  if GOOGLE_PREDICT_FALSE(!IsValidNumericCast<RangeType>(value)) {
-    OutOfRangeError(arg);
-    return false;
-  }
-  return true;
-}
-
 template<class T>
-bool CheckAndGetInteger(PyObject* arg, T* value) {
-  // The fast path.
+bool CheckAndGetInteger(
+    PyObject* arg, T* value, PyObject* min, PyObject* max) {
+  bool is_long = PyLong_Check(arg);
 #if PY_MAJOR_VERSION < 3
-  // For the typical case, offer a fast path.
-  if GOOGLE_PREDICT_TRUE(PyInt_Check(arg)) {
-    long int_result =  PyInt_AsLong(arg);
-    if GOOGLE_PREDICT_TRUE(IsValidNumericCast<T>(int_result)) {
-      *value = static_cast<T>(int_result);
-      return true;
-    } else {
-      OutOfRangeError(arg);
-      return false;
-    }
-  }
-#endif
-  // This effectively defines an integer as "an object that can be cast as
-  // an integer and can be used as an ordinal number".
-  // This definition includes everything that implements numbers.Integral
-  // and shouldn't cast the net too wide.
-  if GOOGLE_PREDICT_FALSE(!PyIndex_Check(arg)) {
+  if (!PyInt_Check(arg) && !is_long) {
     FormatTypeError(arg, "int, long");
     return false;
   }
-
-  // Now we have an integral number so we can safely use PyLong_ functions.
-  // We need to treat the signed and unsigned cases differently in case arg is
-  // holding a value above the maximum for signed longs.
-  if (std::numeric_limits<T>::min() == 0) {
-    // Unsigned case.
-    unsigned PY_LONG_LONG ulong_result;
-    if (PyLong_Check(arg)) {
-      ulong_result = PyLong_AsUnsignedLongLong(arg);
-    } else {
-      // Unlike PyLong_AsLongLong, PyLong_AsUnsignedLongLong is very
-      // picky about the exact type.
-      PyObject* casted = PyNumber_Long(arg);
-      if GOOGLE_PREDICT_FALSE(casted == NULL) {
-        // Propagate existing error.
-        return false;
-      }
-      ulong_result = PyLong_AsUnsignedLongLong(casted);
-      Py_DECREF(casted);
-    }
-    if (VerifyIntegerCastAndRange<T, unsigned PY_LONG_LONG>(arg,
-                                                            ulong_result)) {
-      *value = static_cast<T>(ulong_result);
-    } else {
-      return false;
-    }
-  } else {
-    // Signed case.
-    PY_LONG_LONG long_result;
-    PyNumberMethods *nb;
-    if ((nb = arg->ob_type->tp_as_number) != NULL && nb->nb_int != NULL) {
-      // PyLong_AsLongLong requires it to be a long or to have an __int__()
-      // method.
-      long_result = PyLong_AsLongLong(arg);
-    } else {
-      // Valid subclasses of numbers.Integral should have a __long__() method
-      // so fall back to that.
-      PyObject* casted = PyNumber_Long(arg);
-      if GOOGLE_PREDICT_FALSE(casted == NULL) {
-        // Propagate existing error.
-        return false;
+  if (PyObject_Compare(min, arg) > 0 || PyObject_Compare(max, arg) < 0) {
+#else
+  if (!is_long) {
+    FormatTypeError(arg, "int");
+    return false;
+  }
+  if (PyObject_RichCompareBool(min, arg, Py_LE) != 1 ||
+      PyObject_RichCompareBool(max, arg, Py_GE) != 1) {
+#endif
+    if (!PyErr_Occurred()) {
+      PyObject *s = PyObject_Str(arg);
+      if (s) {
+        PyErr_Format(PyExc_ValueError,
+                     "Value out of range: %s",
+                     PyString_AsString(s));
+        Py_DECREF(s);
       }
-      long_result = PyLong_AsLongLong(casted);
-      Py_DECREF(casted);
     }
-    if (VerifyIntegerCastAndRange<T, PY_LONG_LONG>(arg, long_result)) {
-      *value = static_cast<T>(long_result);
+    return false;
+  }
+#if PY_MAJOR_VERSION < 3
+  if (!is_long) {
+    *value = static_cast<T>(PyInt_AsLong(arg));
+  } else  // NOLINT
+#endif
+  {
+    if (min == kPythonZero) {
+      *value = static_cast<T>(PyLong_AsUnsignedLongLong(arg));
     } else {
-      return false;
+      *value = static_cast<T>(PyLong_AsLongLong(arg));
     }
   }
-
   return true;
 }
 
 // These are referenced by repeated_scalar_container, and must
 // be explicitly instantiated.
-template bool CheckAndGetInteger<int32>(PyObject*, int32*);
-template bool CheckAndGetInteger<int64>(PyObject*, int64*);
-template bool CheckAndGetInteger<uint32>(PyObject*, uint32*);
-template bool CheckAndGetInteger<uint64>(PyObject*, uint64*);
+template bool CheckAndGetInteger<int32>(
+    PyObject*, int32*, PyObject*, PyObject*);
+template bool CheckAndGetInteger<int64>(
+    PyObject*, int64*, PyObject*, PyObject*);
+template bool CheckAndGetInteger<uint32>(
+    PyObject*, uint32*, PyObject*, PyObject*);
+template bool CheckAndGetInteger<uint64>(
+    PyObject*, uint64*, PyObject*, PyObject*);
 
 bool CheckAndGetDouble(PyObject* arg, double* value) {
-  *value = PyFloat_AsDouble(arg);
-  if GOOGLE_PREDICT_FALSE(*value == -1 && PyErr_Occurred()) {
+  if (!PyInt_Check(arg) && !PyLong_Check(arg) &&
+      !PyFloat_Check(arg)) {
     FormatTypeError(arg, "int, long, float");
     return false;
   }
+  *value = PyFloat_AsDouble(arg);
   return true;
 }
 
@@ -715,13 +620,11 @@ bool CheckAndGetFloat(PyObject* arg, float* value) {
 }
 
 bool CheckAndGetBool(PyObject* arg, bool* value) {
-  long long_value = PyInt_AsLong(arg);
-  if (long_value == -1 && PyErr_Occurred()) {
+  if (!PyInt_Check(arg) && !PyBool_Check(arg) && !PyLong_Check(arg)) {
     FormatTypeError(arg, "int, long, bool");
     return false;
   }
-  *value = static_cast<bool>(long_value);
-
+  *value = static_cast<bool>(PyInt_AsLong(arg));
   return true;
 }
 
@@ -849,9 +752,15 @@ bool CheckFieldBelongsToMessage(const FieldDescriptor* field_descriptor,
 
 namespace cmessage {
 
-PyMessageFactory* GetFactoryForMessage(CMessage* message) {
+PyDescriptorPool* GetDescriptorPoolForMessage(CMessage* message) {
+  // No need to check the type: the type of instances of CMessage is always
+  // an instance of CMessageClass. Let's prove it with a debug-only check.
   GOOGLE_DCHECK(PyObject_TypeCheck(message, &CMessage_Type));
-  return reinterpret_cast<CMessageClass*>(Py_TYPE(message))->py_message_factory;
+  return reinterpret_cast<CMessageClass*>(Py_TYPE(message))->py_descriptor_pool;
+}
+
+MessageFactory* GetFactoryForMessage(CMessage* message) {
+  return GetDescriptorPoolForMessage(message)->message_factory;
 }
 
 static int MaybeReleaseOverlappingOneofField(
@@ -904,8 +813,7 @@ static Message* GetMutableMessage(
     return NULL;
   }
   return reflection->MutableMessage(
-      parent_message, parent_field,
-      GetFactoryForMessage(parent)->message_factory);
+      parent_message, parent_field, GetFactoryForMessage(parent));
 }
 
 struct FixupMessageReference : public ChildVisitor {
@@ -1053,7 +961,20 @@ int InternalDeleteRepeatedField(
   int min, max;
   length = reflection->FieldSize(*message, field_descriptor);
 
-  if (PySlice_Check(slice)) {
+  if (PyInt_Check(slice) || PyLong_Check(slice)) {
+    from = to = PyLong_AsLong(slice);
+    if (from < 0) {
+      from = to = length + from;
+    }
+    step = 1;
+    min = max = from;
+
+    // Range check.
+    if (from < 0 || from >= length) {
+      PyErr_Format(PyExc_IndexError, "list assignment index out of range");
+      return -1;
+    }
+  } else if (PySlice_Check(slice)) {
     from = to = step = slice_length = 0;
     PySlice_GetIndicesEx(
 #if PY_MAJOR_VERSION < 3
@@ -1070,23 +991,8 @@ int InternalDeleteRepeatedField(
       max = from;
     }
   } else {
-    from = to = PyLong_AsLong(slice);
-    if (from == -1 && PyErr_Occurred()) {
-      PyErr_SetString(PyExc_TypeError, "list indices must be integers");
-      return -1;
-    }
-
-    if (from < 0) {
-      from = to = length + from;
-    }
-    step = 1;
-    min = max = from;
-
-    // Range check.
-    if (from < 0 || from >= length) {
-      PyErr_Format(PyExc_IndexError, "list assignment index out of range");
-      return -1;
-    }
+    PyErr_SetString(PyExc_TypeError, "list indices must be integers");
+    return -1;
   }
 
   Py_ssize_t i = from;
@@ -1135,12 +1041,7 @@ int InternalDeleteRepeatedField(
 }
 
 // Initializes fields of a message. Used in constructors.
-int InitAttributes(CMessage* self, PyObject* args, PyObject* kwargs) {
-  if (args != NULL && PyTuple_Size(args) != 0) {
-    PyErr_SetString(PyExc_TypeError, "No positional arguments allowed");
-    return -1;
-  }
-
+int InitAttributes(CMessage* self, PyObject* kwargs) {
   if (kwargs == NULL) {
     return 0;
   }
@@ -1266,9 +1167,7 @@ int InitAttributes(CMessage* self, PyObject* args, PyObject* kwargs) {
       }
       CMessage* cmessage = reinterpret_cast<CMessage*>(message.get());
       if (PyDict_Check(value)) {
-        // Make the message exist even if the dict is empty.
-        AssureWritable(cmessage);
-        if (InitAttributes(cmessage, NULL, value) < 0) {
+        if (InitAttributes(cmessage, value) < 0) {
           return -1;
         }
       } else {
@@ -1327,7 +1226,7 @@ static PyObject* New(PyTypeObject* cls,
   if (message_descriptor == NULL) {
     return NULL;
   }
-  const Message* default_message = type->py_message_factory->message_factory
+  const Message* default_message = type->py_descriptor_pool->message_factory
                                    ->GetPrototype(message_descriptor);
   if (default_message == NULL) {
     PyErr_SetString(PyExc_TypeError, message_descriptor->full_name().c_str());
@@ -1346,7 +1245,12 @@ static PyObject* New(PyTypeObject* cls,
 // The __init__ method of Message classes.
 // It initializes fields from keywords passed to the constructor.
 static int Init(CMessage* self, PyObject* args, PyObject* kwargs) {
-  return InitAttributes(self, args, kwargs);
+  if (PyTuple_Size(args) != 0) {
+    PyErr_SetString(PyExc_TypeError, "No positional arguments allowed");
+    return -1;
+  }
+
+  return InitAttributes(self, kwargs);
 }
 
 // ---------------------------------------------------------------------
@@ -1388,9 +1292,6 @@ struct ClearWeakReferences : public ChildVisitor {
 };
 
 static void Dealloc(CMessage* self) {
-  if (self->weakreflist) {
-    PyObject_ClearWeakRefs(reinterpret_cast<PyObject*>(self));
-  }
   // Null out all weak references from children to this message.
   GOOGLE_CHECK_EQ(0, ForEachCompositeField(self, ClearWeakReferences()));
   if (self->extensions) {
@@ -1558,20 +1459,18 @@ PyObject* HasField(CMessage* self, PyObject* arg) {
 }
 
 PyObject* ClearExtension(CMessage* self, PyObject* extension) {
-  const FieldDescriptor* descriptor = GetExtensionDescriptor(extension);
-  if (descriptor == NULL) {
-    return NULL;
-  }
   if (self->extensions != NULL) {
-    PyObject* value = PyDict_GetItem(self->extensions->values, extension);
-    if (value != NULL) {
-      if (InternalReleaseFieldByDescriptor(self, descriptor, value) < 0) {
-        return NULL;
-      }
-      PyDict_DelItem(self->extensions->values, extension);
+    return extension_dict::ClearExtension(self->extensions, extension);
+  } else {
+    const FieldDescriptor* descriptor = GetExtensionDescriptor(extension);
+    if (descriptor == NULL) {
+      return NULL;
+    }
+    if (ScopedPyObjectPtr(ClearFieldByDescriptor(self, descriptor)) == NULL) {
+      return NULL;
     }
   }
-  return ClearFieldByDescriptor(self, descriptor);
+  Py_RETURN_NONE;
 }
 
 PyObject* HasExtension(CMessage* self, PyObject* extension) {
@@ -1657,7 +1556,7 @@ int SetOwner(CMessage* self, const shared_ptr<Message>& new_owner) {
 Message* ReleaseMessage(CMessage* self,
                         const Descriptor* descriptor,
                         const FieldDescriptor* field_descriptor) {
-  MessageFactory* message_factory = GetFactoryForMessage(self)->message_factory;
+  MessageFactory* message_factory = GetFactoryForMessage(self);
   Message* released_message = self->message->GetReflection()->ReleaseMessage(
       self->message, field_descriptor, message_factory);
   // ReleaseMessage will return NULL which differs from
@@ -1694,20 +1593,23 @@ struct ReleaseChild : public ChildVisitor {
       parent_(parent) {}
 
   int VisitRepeatedCompositeContainer(RepeatedCompositeContainer* container) {
-    return repeated_composite_container::Release(container);
+    return repeated_composite_container::Release(
+        reinterpret_cast<RepeatedCompositeContainer*>(container));
   }
 
   int VisitRepeatedScalarContainer(RepeatedScalarContainer* container) {
-    return repeated_scalar_container::Release(container);
+    return repeated_scalar_container::Release(
+        reinterpret_cast<RepeatedScalarContainer*>(container));
   }
 
   int VisitMapContainer(MapContainer* container) {
-    return container->Release();
+    return reinterpret_cast<MapContainer*>(container)->Release();
   }
 
   int VisitCMessage(CMessage* cmessage,
                     const FieldDescriptor* field_descriptor) {
-    return ReleaseSubMessage(parent_, field_descriptor, cmessage);
+    return ReleaseSubMessage(parent_, field_descriptor,
+        reinterpret_cast<CMessage*>(cmessage));
   }
 
   CMessage* parent_;
@@ -1725,19 +1627,12 @@ int InternalReleaseFieldByDescriptor(
 
 PyObject* ClearFieldByDescriptor(
     CMessage* self,
-    const FieldDescriptor* field_descriptor) {
-  if (!CheckFieldBelongsToMessage(field_descriptor, self->message)) {
+    const FieldDescriptor* descriptor) {
+  if (!CheckFieldBelongsToMessage(descriptor, self->message)) {
     return NULL;
   }
   AssureWritable(self);
-  Message* message = self->message;
-  message->GetReflection()->ClearField(message, field_descriptor);
-  if (field_descriptor->cpp_type() == FieldDescriptor::CPPTYPE_ENUM &&
-      !message->GetReflection()->SupportsUnknownEnumValues()) {
-    UnknownFieldSet* unknown_field_set =
-        message->GetReflection()->MutableUnknownFields(message);
-    unknown_field_set->DeleteByNumber(field_descriptor->number());
-  }
+  self->message->GetReflection()->ClearField(self->message, descriptor);
   Py_RETURN_NONE;
 }
 
@@ -1773,17 +1668,27 @@ PyObject* ClearField(CMessage* self, PyObject* arg) {
     arg = arg_in_oneof.get();
   }
 
-  // Release the field if it exists in the dict of composite fields.
-  if (self->composite_fields) {
-    PyObject* value = PyDict_GetItem(self->composite_fields, arg);
-    if (value != NULL) {
-      if (InternalReleaseFieldByDescriptor(self, field_descriptor, value) < 0) {
-        return NULL;
-      }
-      PyDict_DelItem(self->composite_fields, arg);
+  PyObject* composite_field = self->composite_fields ?
+      PyDict_GetItem(self->composite_fields, arg) : NULL;
+
+  // Only release the field if there's a possibility that there are
+  // references to it.
+  if (composite_field != NULL) {
+    if (InternalReleaseFieldByDescriptor(self, field_descriptor,
+                                         composite_field) < 0) {
+      return NULL;
     }
+    PyDict_DelItem(self->composite_fields, arg);
+  }
+  message->GetReflection()->ClearField(message, field_descriptor);
+  if (field_descriptor->cpp_type() == FieldDescriptor::CPPTYPE_ENUM &&
+      !message->GetReflection()->SupportsUnknownEnumValues()) {
+    UnknownFieldSet* unknown_field_set =
+        message->GetReflection()->MutableUnknownFields(message);
+    unknown_field_set->DeleteByNumber(field_descriptor->number());
   }
-  return ClearFieldByDescriptor(self, field_descriptor);
+
+  Py_RETURN_NONE;
 }
 
 PyObject* Clear(CMessage* self) {
@@ -1994,15 +1899,11 @@ static PyObject* CopyFrom(CMessage* self, PyObject* arg) {
 // get OOM errors. The protobuf APIs do not provide any tools for processing
 // protobufs in chunks.  If you have protos this big you should break them up if
 // it is at all convenient to do so.
-#ifdef PROTOBUF_PYTHON_ALLOW_OVERSIZE_PROTOS
-static bool allow_oversize_protos = true;
-#else
 static bool allow_oversize_protos = false;
-#endif
 
 // Provide a method in the module to set allow_oversize_protos to a boolean
 // value. This method returns the newly value of allow_oversize_protos.
-PyObject* SetAllowOversizeProtos(PyObject* m, PyObject* arg) {
+static PyObject* SetAllowOversizeProtos(PyObject* m, PyObject* arg) {
   if (!arg || !PyBool_Check(arg)) {
     PyErr_SetString(PyExc_TypeError,
                     "Argument to SetAllowOversizeProtos must be boolean");
@@ -2029,8 +1930,8 @@ static PyObject* MergeFromString(CMessage* self, PyObject* arg) {
   if (allow_oversize_protos) {
     input.SetTotalBytesLimit(INT_MAX, INT_MAX);
   }
-  PyMessageFactory* factory = GetFactoryForMessage(self);
-  input.SetExtensionRegistry(factory->pool->pool, factory->message_factory);
+  PyDescriptorPool* pool = GetDescriptorPoolForMessage(self);
+  input.SetExtensionRegistry(pool->pool, pool->message_factory);
   bool success = self->message->MergePartialFromCodedStream(&input);
   if (success) {
     return PyInt_FromLong(input.CurrentPosition());
@@ -2051,29 +1952,99 @@ static PyObject* ByteSize(CMessage* self, PyObject* args) {
   return PyLong_FromLong(self->message->ByteSize());
 }
 
-PyObject* RegisterExtension(PyObject* cls, PyObject* extension_handle) {
+static PyObject* RegisterExtension(PyObject* cls,
+                                   PyObject* extension_handle) {
   const FieldDescriptor* descriptor =
       GetExtensionDescriptor(extension_handle);
   if (descriptor == NULL) {
     return NULL;
   }
-  if (!PyObject_TypeCheck(cls, &CMessageClass_Type)) {
-    PyErr_Format(PyExc_TypeError, "Expected a message class, got %s",
-                 cls->ob_type->tp_name);
+
+  ScopedPyObjectPtr extensions_by_name(
+      PyObject_GetAttr(cls, k_extensions_by_name));
+  if (extensions_by_name == NULL) {
+    PyErr_SetString(PyExc_TypeError, "no extensions_by_name on class");
     return NULL;
   }
-  CMessageClass *message_class = reinterpret_cast<CMessageClass*>(cls);
-  if (message_class == NULL) {
+  ScopedPyObjectPtr full_name(PyObject_GetAttr(extension_handle, kfull_name));
+  if (full_name == NULL) {
     return NULL;
   }
+
   // If the extension was already registered, check that it is the same.
-  const FieldDescriptor* existing_extension =
-      message_class->py_message_factory->pool->pool->FindExtensionByNumber(
-          descriptor->containing_type(), descriptor->number());
-  if (existing_extension != NULL && existing_extension != descriptor) {
-    PyErr_SetString(PyExc_ValueError, "Double registration of Extensions");
+  PyObject* existing_extension =
+      PyDict_GetItem(extensions_by_name.get(), full_name.get());
+  if (existing_extension != NULL) {
+    const FieldDescriptor* existing_extension_descriptor =
+        GetExtensionDescriptor(existing_extension);
+    if (existing_extension_descriptor != descriptor) {
+      PyErr_SetString(PyExc_ValueError, "Double registration of Extensions");
+      return NULL;
+    }
+    // Nothing else to do.
+    Py_RETURN_NONE;
+  }
+
+  if (PyDict_SetItem(extensions_by_name.get(), full_name.get(),
+                     extension_handle) < 0) {
+    return NULL;
+  }
+
+  // Also store a mapping from extension number to implementing class.
+  ScopedPyObjectPtr extensions_by_number(
+      PyObject_GetAttr(cls, k_extensions_by_number));
+  if (extensions_by_number == NULL) {
+    PyErr_SetString(PyExc_TypeError, "no extensions_by_number on class");
     return NULL;
   }
+
+  ScopedPyObjectPtr number(PyObject_GetAttrString(extension_handle, "number"));
+  if (number == NULL) {
+    return NULL;
+  }
+
+  // If the extension was already registered by number, check that it is the
+  // same.
+  existing_extension = PyDict_GetItem(extensions_by_number.get(), number.get());
+  if (existing_extension != NULL) {
+    const FieldDescriptor* existing_extension_descriptor =
+        GetExtensionDescriptor(existing_extension);
+    if (existing_extension_descriptor != descriptor) {
+      const Descriptor* msg_desc = GetMessageDescriptor(
+          reinterpret_cast<PyTypeObject*>(cls));
+      PyErr_Format(
+          PyExc_ValueError,
+          "Extensions \"%s\" and \"%s\" both try to extend message type "
+          "\"%s\" with field number %ld.",
+          existing_extension_descriptor->full_name().c_str(),
+          descriptor->full_name().c_str(),
+          msg_desc->full_name().c_str(),
+          PyInt_AsLong(number.get()));
+      return NULL;
+    }
+    // Nothing else to do.
+    Py_RETURN_NONE;
+  }
+  if (PyDict_SetItem(extensions_by_number.get(), number.get(),
+                     extension_handle) < 0) {
+    return NULL;
+  }
+
+  // Check if it's a message set
+  if (descriptor->is_extension() &&
+      descriptor->containing_type()->options().message_set_wire_format() &&
+      descriptor->type() == FieldDescriptor::TYPE_MESSAGE &&
+      descriptor->label() == FieldDescriptor::LABEL_OPTIONAL) {
+    ScopedPyObjectPtr message_name(PyString_FromStringAndSize(
+        descriptor->message_type()->full_name().c_str(),
+        descriptor->message_type()->full_name().size()));
+    if (message_name == NULL) {
+      return NULL;
+    }
+    PyDict_SetItem(extensions_by_name.get(), message_name.get(),
+                   extension_handle);
+  }
+
   Py_RETURN_NONE;
 }
 
@@ -2110,7 +2081,7 @@ static PyObject* WhichOneof(CMessage* self, PyObject* arg) {
 static PyObject* GetExtensionDict(CMessage* self, void *closure);
 
 static PyObject* ListFields(CMessage* self) {
-  std::vector<const FieldDescriptor*> fields;
+  vector<const FieldDescriptor*> fields;
   self->message->GetReflection()->ListFields(*self->message, &fields);
 
   // Normally, the list will be exactly the size of the fields.
@@ -2140,8 +2111,8 @@ static PyObject* ListFields(CMessage* self) {
       // is no message class and we cannot retrieve the value.
       // TODO(amauryfa): consider building the class on the fly!
       if (fields[i]->message_type() != NULL &&
-          message_factory::GetMessageClass(
-              GetFactoryForMessage(self),
+          cdescriptor_pool::GetMessageClass(
+              GetDescriptorPoolForMessage(self),
               fields[i]->message_type()) == NULL) {
         PyErr_Clear();
         continue;
@@ -2201,7 +2172,7 @@ static PyObject* DiscardUnknownFields(CMessage* self) {
 
 PyObject* FindInitializationErrors(CMessage* self) {
   Message* message = self->message;
-  std::vector<string> errors;
+  vector<string> errors;
   message->FindInitializationErrors(&errors);
 
   PyObject* error_list = PyList_New(errors.size());
@@ -2338,12 +2309,12 @@ PyObject* InternalGetScalar(const Message* message,
 PyObject* InternalGetSubMessage(
     CMessage* self, const FieldDescriptor* field_descriptor) {
   const Reflection* reflection = self->message->GetReflection();
-  PyMessageFactory* factory = GetFactoryForMessage(self);
+  PyDescriptorPool* pool = GetDescriptorPoolForMessage(self);
   const Message& sub_message = reflection->GetMessage(
-      *self->message, field_descriptor, factory->message_factory);
+      *self->message, field_descriptor, pool->message_factory);
 
-  CMessageClass* message_class = message_factory::GetMessageClass(
-      factory, field_descriptor->message_type());
+  CMessageClass* message_class = cdescriptor_pool::GetMessageClass(
+      pool, field_descriptor->message_type());
   if (message_class == NULL) {
     return NULL;
   }
@@ -2593,24 +2564,11 @@ static PyObject* GetExtensionDict(CMessage* self, void *closure) {
   return NULL;
 }
 
-static PyObject* GetExtensionsByName(CMessage *self, void *closure) {
-  return message_meta::GetExtensionsByName(
-      reinterpret_cast<CMessageClass*>(Py_TYPE(self)), closure);
-}
-
-static PyObject* GetExtensionsByNumber(CMessage *self, void *closure) {
-  return message_meta::GetExtensionsByNumber(
-      reinterpret_cast<CMessageClass*>(Py_TYPE(self)), closure);
-}
-
 static PyGetSetDef Getters[] = {
   {"Extensions", (getter)GetExtensionDict, NULL, "Extension dict"},
-  {"_extensions_by_name", (getter)GetExtensionsByName, NULL},
-  {"_extensions_by_number", (getter)GetExtensionsByNumber, NULL},
   {NULL}
 };
 
-
 static PyMethodDef Methods[] = {
   { "__deepcopy__", (PyCFunction)DeepCopy, METH_VARARGS,
     "Makes a deep copy of the class." },
@@ -2701,8 +2659,8 @@ PyObject* GetAttr(CMessage* self, PyObject* name) {
     const Descriptor* entry_type = field_descriptor->message_type();
     const FieldDescriptor* value_type = entry_type->FindFieldByName("value");
     if (value_type->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
-      CMessageClass* value_class = message_factory::GetMessageClass(
-          GetFactoryForMessage(self), value_type->message_type());
+      CMessageClass* value_class = cdescriptor_pool::GetMessageClass(
+          GetDescriptorPoolForMessage(self), value_type->message_type());
       if (value_class == NULL) {
         return NULL;
       }
@@ -2724,8 +2682,8 @@ PyObject* GetAttr(CMessage* self, PyObject* name) {
   if (field_descriptor->label() == FieldDescriptor::LABEL_REPEATED) {
     PyObject* py_container = NULL;
     if (field_descriptor->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
-      CMessageClass* message_class = message_factory::GetMessageClass(
-          GetFactoryForMessage(self), field_descriptor->message_type());
+      CMessageClass* message_class = cdescriptor_pool::GetMessageClass(
+          GetDescriptorPoolForMessage(self), field_descriptor->message_type());
       if (message_class == NULL) {
         return NULL;
       }
@@ -2820,7 +2778,7 @@ PyTypeObject CMessage_Type = {
   0,                                   //  tp_traverse
   0,                                   //  tp_clear
   (richcmpfunc)cmessage::RichCompare,  //  tp_richcompare
-  offsetof(CMessage, weakreflist),     //  tp_weaklistoffset
+  0,                                   //  tp_weaklistoffset
   0,                                   //  tp_iter
   0,                                   //  tp_iternext
   cmessage::Methods,                   //  tp_methods
@@ -2867,11 +2825,30 @@ static Message* MutableCProtoInsidePyProtoImpl(PyObject* msg) {
   return cmsg->message;
 }
 
+static const char module_docstring[] =
+"python-proto2 is a module that can be used to enhance proto2 Python API\n"
+"performance.\n"
+"\n"
+"It provides access to the protocol buffers C++ reflection API that\n"
+"implements the basic protocol buffer functions.";
+
 void InitGlobals() {
   // TODO(gps): Check all return values in this function for NULL and propagate
   // the error (MemoryError) on up to result in an import failure.  These should
   // also be freed and reset to NULL during finalization.
+  kPythonZero = PyInt_FromLong(0);
+  kint32min_py = PyInt_FromLong(kint32min);
+  kint32max_py = PyInt_FromLong(kint32max);
+  kuint32max_py = PyLong_FromLongLong(kuint32max);
+  kint64min_py = PyLong_FromLongLong(kint64min);
+  kint64max_py = PyLong_FromLongLong(kint64max);
+  kuint64max_py = PyLong_FromUnsignedLongLong(kuint64max);
+
   kDESCRIPTOR = PyString_FromString("DESCRIPTOR");
+  k_cdescriptor = PyString_FromString("_cdescriptor");
+  kfull_name = PyString_FromString("full_name");
+  k_extensions_by_name = PyString_FromString("_extensions_by_name");
+  k_extensions_by_number = PyString_FromString("_extensions_by_number");
 
   PyObject *dummy_obj = PySet_New(NULL);
   kEmptyWeakref = PyWeakref_NewRef(dummy_obj, NULL);
@@ -2889,11 +2866,6 @@ bool InitProto2MessageModule(PyObject *m) {
     return false;
   }
 
-  // Initialize types and globals in message_factory.cc
-  if (!InitMessageFactory()) {
-    return false;
-  }
-
   // Initialize constants defined in this file.
   InitGlobals();
 
@@ -2911,6 +2883,25 @@ bool InitProto2MessageModule(PyObject *m) {
   // DESCRIPTOR is set on each protocol buffer message class elsewhere, but set
   // it here as well to document that subclasses need to set it.
   PyDict_SetItem(CMessage_Type.tp_dict, kDESCRIPTOR, Py_None);
+  // Subclasses with message extensions will override _extensions_by_name and
+  // _extensions_by_number with fresh mutable dictionaries in AddDescriptors.
+  // All other classes can share this same immutable mapping.
+  ScopedPyObjectPtr empty_dict(PyDict_New());
+  if (empty_dict == NULL) {
+    return false;
+  }
+  ScopedPyObjectPtr immutable_dict(PyDictProxy_New(empty_dict.get()));
+  if (immutable_dict == NULL) {
+    return false;
+  }
+  if (PyDict_SetItem(CMessage_Type.tp_dict,
+                     k_extensions_by_name, immutable_dict.get()) < 0) {
+    return false;
+  }
+  if (PyDict_SetItem(CMessage_Type.tp_dict,
+                     k_extensions_by_number, immutable_dict.get()) < 0) {
+    return false;
+  }
 
   PyModule_AddObject(m, "Message", reinterpret_cast<PyObject*>(&CMessage_Type));
 
@@ -2956,15 +2947,69 @@ bool InitProto2MessageModule(PyObject *m) {
   }
 
   // Initialize Map container types.
-  if (!InitMapContainers()) {
-    return false;
+  {
+    // ScalarMapContainer_Type derives from our MutableMapping type.
+    ScopedPyObjectPtr containers(PyImport_ImportModule(
+        "google.protobuf.internal.containers"));
+    if (containers == NULL) {
+      return false;
+    }
+
+    ScopedPyObjectPtr mutable_mapping(
+        PyObject_GetAttrString(containers.get(), "MutableMapping"));
+    if (mutable_mapping == NULL) {
+      return false;
+    }
+
+    if (!PyObject_TypeCheck(mutable_mapping.get(), &PyType_Type)) {
+      return false;
+    }
+
+    Py_INCREF(mutable_mapping.get());
+#if PY_MAJOR_VERSION >= 3
+    PyObject* bases = PyTuple_New(1);
+    PyTuple_SET_ITEM(bases, 0, mutable_mapping.get());
+
+    ScalarMapContainer_Type = 
+        PyType_FromSpecWithBases(&ScalarMapContainer_Type_spec, bases);
+    PyModule_AddObject(m, "ScalarMapContainer", ScalarMapContainer_Type);
+#else
+    ScalarMapContainer_Type.tp_base =
+        reinterpret_cast<PyTypeObject*>(mutable_mapping.get());
+
+    if (PyType_Ready(&ScalarMapContainer_Type) < 0) {
+      return false;
+    }
+
+    PyModule_AddObject(m, "ScalarMapContainer",
+                       reinterpret_cast<PyObject*>(&ScalarMapContainer_Type));
+#endif
+
+    if (PyType_Ready(&MapIterator_Type) < 0) {
+      return false;
+    }
+
+    PyModule_AddObject(m, "MapIterator",
+                       reinterpret_cast<PyObject*>(&MapIterator_Type));
+
+
+#if PY_MAJOR_VERSION >= 3
+    MessageMapContainer_Type = 
+        PyType_FromSpecWithBases(&MessageMapContainer_Type_spec, bases);
+    PyModule_AddObject(m, "MessageMapContainer", MessageMapContainer_Type);
+#else
+    Py_INCREF(mutable_mapping.get());
+    MessageMapContainer_Type.tp_base =
+        reinterpret_cast<PyTypeObject*>(mutable_mapping.get());
+
+    if (PyType_Ready(&MessageMapContainer_Type) < 0) {
+      return false;
+    }
+
+    PyModule_AddObject(m, "MessageMapContainer",
+                       reinterpret_cast<PyObject*>(&MessageMapContainer_Type));
+#endif
   }
-  PyModule_AddObject(m, "ScalarMapContainer",
-                     reinterpret_cast<PyObject*>(ScalarMapContainer_Type));
-  PyModule_AddObject(m, "MessageMapContainer",
-                     reinterpret_cast<PyObject*>(MessageMapContainer_Type));
-  PyModule_AddObject(m, "MapIterator",
-                     reinterpret_cast<PyObject*>(&MapIterator_Type));
 
   if (PyType_Ready(&ExtensionDict_Type) < 0) {
     return false;
@@ -2999,10 +3044,6 @@ bool InitProto2MessageModule(PyObject *m) {
       &PyFileDescriptor_Type));
   PyModule_AddObject(m, "OneofDescriptor", reinterpret_cast<PyObject*>(
       &PyOneofDescriptor_Type));
-  PyModule_AddObject(m, "ServiceDescriptor", reinterpret_cast<PyObject*>(
-      &PyServiceDescriptor_Type));
-  PyModule_AddObject(m, "MethodDescriptor", reinterpret_cast<PyObject*>(
-      &PyMethodDescriptor_Type));
 
   PyObject* enum_type_wrapper = PyImport_ImportModule(
       "google.protobuf.internal.enum_type_wrapper");
@@ -3040,4 +3081,53 @@ bool InitProto2MessageModule(PyObject *m) {
 }  // namespace python
 }  // namespace protobuf
 
+static PyMethodDef ModuleMethods[] = {
+  {"SetAllowOversizeProtos",
+    (PyCFunction)google::protobuf::python::cmessage::SetAllowOversizeProtos,
+    METH_O, "Enable/disable oversize proto parsing."},
+  { NULL, NULL}
+};
+
+#if PY_MAJOR_VERSION >= 3
+static struct PyModuleDef _module = {
+  PyModuleDef_HEAD_INIT,
+  "_message",
+  google::protobuf::python::module_docstring,
+  -1,
+  ModuleMethods,  /* m_methods */
+  NULL,
+  NULL,
+  NULL,
+  NULL
+};
+#define INITFUNC PyInit__message
+#define INITFUNC_ERRORVAL NULL
+#else  // Python 2
+#define INITFUNC init_message
+#define INITFUNC_ERRORVAL
+#endif
+
+extern "C" {
+  PyMODINIT_FUNC INITFUNC(void) {
+    PyObject* m;
+#if PY_MAJOR_VERSION >= 3
+    m = PyModule_Create(&_module);
+#else
+    m = Py_InitModule3("_message", ModuleMethods,
+                       google::protobuf::python::module_docstring);
+#endif
+    if (m == NULL) {
+      return INITFUNC_ERRORVAL;
+    }
+
+    if (!google::protobuf::python::InitProto2MessageModule(m)) {
+      Py_DECREF(m);
+      return INITFUNC_ERRORVAL;
+    }
+
+#if PY_MAJOR_VERSION >= 3
+    return m;
+#endif
+  }
+}
 }  // namespace google